Sewage tank



FIG. 1 is a perspective view of a sewage tank in accordance with the new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side elevational view thereof, a left side elevational view being a mirror image thereof;

FIG. 4 is a rear elevational view thereof; and,

FIG. 5 is a top view thereof. 

The ornamental design for a sewage tank, as shown and described. 